I had this crop up in my herd once from a rabbit that was given to me. Since she was in isolation it was simply a matter of treating her.
Vent disease is not a particularly good disease to have in your rabbitry and often requires all rabbits to be treated for it.
some resources to pursue in one's search for more knowledge on this disease
Rabbits Online (note this is a rescue forum)
This link has pictures and a variety of links to look through.
According to Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery by Katherine E Quesenberry and James W. Carpenter, my source for this article, penicillin G benzathine-penicillin G procaine (sold as Combi-Pen and commonly referred to as pen B) administered at 7-day intervals for 3 injections (42,000 to 84,0000 IU per kilogram of rabbit weight given subcutaneously) is an appropriate treatment.My Combi-Pen has 300,000 IU per milliliter. A 4-lb. rabbit weighs 1.8 kg. The range for a 4 lb. rabbit is therefore 75,600 to 151,200 IU or 1/4 to 1/2 mililitters or cc’s. The convention many breeders use is 1/10 cc per pound. Please make your own calculations and consult your vet before administering medications.If you use Pen G, then you must give it for 5 to 7 days straight intramuscular. I find this treatment harder on the rabbit’s GI tract, though, and harder to administer. Other breeders have found that vent disease is more likely to reoccur with the Pen G treatment.
Treponematosis, a specific venereal disease of domestic rabbits, is caused by the spirochete Treponema paraluis cuniculi . It occurs in both sexes and is transmitted by coitus and from the doe to offspring. Although closely related to the organism ( T pallidum ) that causes human syphilis, T cuniculi is not transmissible to other domestic animals or humans.